The present invention relates to an apparatus for controlling the flow of ambient air into a plenum and more particularly to an apparatus for controlling the flow of ambient air into a protective shelter such as a tank housing.
It has long been known in the art to provide a protective shelter in a contaminated atmosphere with ambient air flow control apparatus associated with the shelter designed to introduce and filter ambient air introduced into the shelter. Such a protective system arrangement can be found in the unexpired U.S. Pat. No. 3,766,844, issued to Thomas G. Donnelly, et al, on Oct. 23, 1973. It also has been known to control the flow of ambient air into a protective shelter arrangement in such a manner that ventilating air is introduced into the protective shelter through one shelter inlet opening during one mode of operation and filtered ambient air is introduced into the protective shelter through another shelter inlet opening during another mode of operation. Further, it is well known in the valve art to broadly provide a variable flow control arrangement utilizing a valve within a valve such as is disclosed in the now expired U.S. Pat. No. 3,232,315, issued to D. A. Morelli on Feb. 1, 1966 and the now expired U.S. Pat. No. 3,242,943, issued to R. W. Waterfill on Mar. 29, 1966. For the most part, however, the flow control arrangements utilized with protective shelters have been complex and extensive in construction, operation and maintenance and none appear to have utilized the valve-within-a-valve inlet arrangement in any form.
The present invention, recognizing the problems of the past, provides a straightforward protective shelter flow control apparatus which utilizes a valve-within-a-valve arrangement to reduce the number of parts involved providing an apparatus which is efficient and economical in construction, operation and maintenance and requiring a minimum of energy and space.
Although the apparatus of the present invention is here disclosed in use with an armored tank, it is to be understood that the apparatus of the present invention is not limited to use only for military purposes but also can be utilized in any other ambient environment including commercial situations where it is desirable to control air flow into a protective shelter during and after changes in ambient air conditions.
Various other features of the present invention will become obvious to one skilled in the art upon reading the description of the inventive apparatus set forth hereinafter.